With the growing popularity of functional training programs, high intensity programs & around the gym floor I’m seeing more and more plyometric training which is AWESOME!! Box jumps, broad jumps, burpees etc, I guarantee plyometrics will take your athletic ability from average to great. But to the “untrained” or “newbie” to these gyms and programs people are dropping out injured before any great results come.
I call this the 8-10 month drop out marker where people start at a gym or a program that assumes you are moving perfectly well and are ready for any kind of training at any rate of intensity.
You don’t buy a used race car without going to the mechanic first, do you?
It usually takes about 8-10 months of high intense work before a dysfunction in movement will present pain, this is why doing a few months of corrective work with proper coaching on how to load joints and distribute ground reaction forces safely has the upmost importance to insure everyone stays in the gym as long as possible without injury.
So, i’m going to discuss three components of a jump that aren’t often taken into consideration. How the force is distributed throughout the body, what strength protocols that should be met before going into plyometric training and how they fit into a workout program.
With a box jump everyone puts all their effort into the jump, which 8-9 times out of 10, doesn’t cause too much damage other than repetitive collapsing of the knees in the power phase or not reaching full hip extension. But that’s a whole other post, in this post, I’m going to discuss the landing phase. Poor technique used to land a box jump is what causes injury, mainly knee, ankle and lower back. Jumping off the box to the ground, in my opinion, requires more strength and technique than jumping up, and has just as much, if not more, importance in your performance.
There are 3 stages of a box jump rep: eccentric (landing), amortization (contact time on ground), and concentric (coming back up). Because not many people have the strength to control the eccentric phase, it is this phase that will cause damage and ruin your amortization phase, which is the whole point of the box jump. A box jump is to express how quick and efficient you can load force on the landing (amortization), then how well you can use the ground reaction force (the energy gathered from landing) to jump back up.
When landing a box jump you are sending up to 20x your body weight through your patellofemoral joint (knee). Knowing that number makes me cringe when I watch how some people dismount a box jump with locked knees, rolling ankles etc, and knowing that all that force is being shot through your tendons and locked joints, not the elastic, energy soaking muscular sling systems you should use.
You’re putting a lot of undue stress on the Achilles (tendon behind your heel) and patellar tendons (tendon under your knee cap) and limiting your ability to cushion with the hip extensors (glutes). Additionally, you’re really increasing the amortization phase, therefore killing the very elastic response you’re trying to train. Defeats the whole purpose of the jump.
If you can’t load it, don’t do it.
Strength & Volume
So, how do you know you’re ready for box jumps?
First, if you walk into a gym or go to a trainer and are given box jumps within your first 1-6 months without any coaching on how to properly load your joints to take and use the ground reaction forces, or haven’t done the necessary strength work for your muscles and tendons to actually handle that huge load turn around and run away… run far away.
Before starting any plyometric exercise or program there are some strength protocols to reach.
Box jumps, being lower body plyo, the athlete needs to be able to perform a squat 1.5x their body weight, the speed requirement is squatting 5 reps at 60% bodyweight in 5 seconds or less and balance being holding a single leg half squat for 30 seconds without falling. (David H. Potach, Donald A. Chu of the Florida A&M University)
Volume in plyometric training is expressed as contacts per week, which have protocols too. If you’re jumping off the box to get back down, you’re actually performing a second plyometric movement and those contacts should be counted as well. Jump up then jump down = 1 box jump but 2 contacts.
For the weekend warrior or un-trained athlete these protocols are essential, as the tendons aren’t strong enough to be taking high volume with high load bashings. Beginner: 30-80 contacts per week, Intermediate: 100-140 contacts and advanced: 140+. Rest periods are 2-3 minutes between 2-6 sets of 1-6 reps max!!!!!
Box jumps are a way more advanced movement than people may think, and are often placed in the wrong phase of programming. We do box jumps to move our limbs faster and therefore lift more, not as a conditioning tool. Using box jumps for conditioning/fat loss tool at high volume and/or speeds leads to a breakdown of form leading to battered shins, twisted and broken ankles, knee injuries, lower back compression injuries and other injuries we’ve discussed. Additionally, it ingrains poor movement mechanics. A box jump is programmed to improve your squat mechanics and performance, not make it worse.
In addition, jumping for high reps and pushing the tempo minimizes full hip-extension, which doesn’t do you any favours. Full hip-extension is the primary driver of a solid vertical jump and transfers to activities like running and the lockout of a deadlift or squat to name a few key movements.
My advice is to just step down off the box, or if you must, work at a low height and focus how your landing, soaking the weight and recoiling the energy back up.
If you would like more advice on technique and proper programming, or if you’ve pushed plyometric work too hard and have caused damage email me at [email protected] and I’ll do my best to help.